Color cinematography, method and apparatus



Patented Sept. 28, 1926.

UNITED v s'raras A y v1,601,616 PATENT OFFICE.

CLAUDE EL FRIESE-GREENE, F BROMLEY, ENGLAND.

COLOR CINEMATOGRAPHY, METHOD AND APPARATUS.

Application led July 16, 1924, SeralNo. 726,398, and in Great BritainMay 21, 1924.

This invention relates to color cinematography in which differentsections of the surlface of a color sensitive or panchromatic film areexposed alternately to light allowed to pass through filters.

tomary to use a disc havin-g a pair of apertures one of which is filledentirely with a lter'of a particular color, the other aperture onlybeing partially covered, generally l0 a relatively small portionthereof, by a filter having a complementary or differentl color. lt .isknown that color sensitive emulsions are more responsive to certaincolors' than they are to others, so that itis necessary to determine thetransmission of color filters through which the film is exposed, whichgive the best results. The portions of the spectrum from which thesecolors are selected are usually from the red side for the wholly coveredaperture, and the blue end for the` other filter which generally alsopasses while light. While this principle gives good results thereis'still room for improvement,

particularly in instances where grass and foliege in its natural greenstate has` to be photographed, also when photographing in a hazy ormisty light, the latter condition often existing almost unsuspectedlyduring very warm and fine weather so that distant definition may beregistered; The object of this invention is vto obtain the foregoing desideratum whereby a more ,perfect reproduch tion of the objectphotographed is obtained, and in which the fault, commonly known asfringing i's obviated to'a minimum, also re'- duction in speed ofprojection being obtained together with a finer color gradation. Broadlythis invention isy characterized in that the film is exposed throughfilters all vof which are substantially of the same tone of color, oneof thefilters having in conjunction with it an opening passing whitelight. In the accompanying drawings, whch are illus`- trative of myyinvention 1n one preferred form:

Fig. l is an elevation `of a rotatable embodying my invention;

Fig. 2, an elevation of a portion of a film colored'in accordance withmyinvention;

and

v Fig'. 3, a view similar to Fig. l showing a slightly modified form fdisk.

in the preferredembodment of this invention the col'or employed for thefilters is 5% substantially selected from the red side of disk Inpractice it is custhe density and tone of the two colored filthe'spectrum. Preferably an ordinary rotating disk A is employed, 'rotatingat 'haif the speed of an ordinary shutter, but having apertures forfilters. -One of these apertures is filled 'entirely with a lter Rhaving 60 la color predominating on the red side of the spectrum. -The-'other aperture is utilized to allow the passage of white light and ispartially filled by a filter r with a color also substantially on thered side of the spectrum. The sections of the film B are exposedalternately through the two apertures specified. The results ofemploying the same color 1n eachl aperture, one of which has an openingallowing the passage of white light gives a result which is appreciablymuch better than any other arrangement of filters heretofore employed,particularlywith regards to the photography-of ass or foliage 1n itsnatural green state, tie picture projected from the positive giving agood green reproduction ofthe grass or foliage, as well as finergradations of other colors with a good distant definition, even whenobjects at a distance are wrapped in mist.

The area of the color filter employed with the opening passing whitelight may be varied, also the area of? white light aperture according tothe balance required, likewise e5 ters may be varied relatively or incommon as desired. The color filter having the .white light opening mayinclude a relatively small proportion of color from the blue part of thespectrum provided that the addition of such blue color will not affectnoticeably the predomination of the approximately red color of thefilter, should it be considered necessary to assist the color gradationson the blue side. Alternatively a relatively small area of approximatelyblue filter hav- 'ing the same effect-as the aforementionedincorporation of blue with red may be used in conjunction with the redfilter and white aperture as shown by dotted lines at c in Fig. 1 of thedrawings. Y

Briefiy it may be stated the preferred embodiment of this inventionresides in employing a disk having two apertures employing4 filterssubstantially red i. e. any 105 J color except that in which the greencolor related to the red side of the spectrum predominates, for instanceorange,v orange red,

and yellow may be employed good examples of suitable dyes beingflavajzine T or rose leins, prepared by treating dichlorfluorescein withiodine. l

In employing this invention the best results are obtained by bringingeach picture into position for exposure in the gate as quickly aspossible, i. e. the rate of change of successive sections to be effectedas quickly4 as possible. Also it is distinctly advanta eous to,lcarefully balance the luminous values of the colors `applied to thepositive film, the colors which are applied to the film being anapproximately orange red and an approximately blue green, the formercolor being applied to those sections of the film which are exposedthrough the wholly red or approximately-red filter, and the othersections being colored with an approximately blue green in known manner.By means of my 4invention' a much more refined and delicate colorgradation is obtained. The quick change feature reduces color fringingto a minimum, and the balance of luminous values reduces flickerandrunning speed during projection. Also owing to the rapid feeding ofthe film through the gate a longer exposure can be given.

If desired the filter` associated with the aperture passing white lightmay be split up into a plurality of portons in conjunction with acorresponding splittingup of' the white light aperture as shown at r',lw Z',

respectively, in Fig. 3 of the drawings.

The accoinpanyinfrdrawing, Fig. 1, gives a good example -of theproportions of filters and white opening to give good results undernormal fine weather conditions, the white light opening being indicatedby the reference W. L. The shaded O part indicates an adjustable opaquefilling. The proportions shown inthe drawing have been found to givegoods resultsby employing a flavazine T and red benvale filter for thefilter R, and a flavazine T filter for the filter r.

The following formulae are suitable for preparing the dyes for thefilters and thev coloring for applying to the positive film.

For the lter R':

Base solution No. 1: flavazine T l gram dissolved i-n 2 oz. of distilledwater.

Base solution No. 2: rose bengale 1 gram dissolved in 1/2 oz. purealcohol and add distilled water up to 2 oz.

Method-Immerse a strip of transparent gelatine in base solution 1 for 30seconds, rinse rapidly in water and allow the gelatine to dry- When dryimmerse same in solution' 2 for one minute then han not rinse thesolution 2).

up to dry (do gelatine after t e immersion in lll/'then the gelatine isdry cut same .tol fit the aperture in the disk.

To make filter r. Use the same formulae as base solution 1 i-inmersing astrip of transparent gelatine in it for 45 seconds, rinse and allow sameto dry. When dry cut to sizey desired.

It is always advisable when filters have been made and set, to'take atest o first so that it is possible to check the balance. A good way ofso doing is to photograph objects white and black, the densityvon theresultant negative' of each should appear equal in -each successivepicture.

Good formulae for dyeing the positive pictures are as follows:

Orange red for the section that has been exposed throughtlie wholly redfilter.

Solution 1: Brilliant red, which is the sodium salt of R-aZo-S toluene psulplion amino 1 naphthol 3:6 disulphonic acid, .l0A

exposed through the white Iopening and flavazine filter.

Lissamine green, which is sodium salt of tetramethylfdiaminodiphenyl Bhydroxynaphthyl-carbinol disulphonic acid anhydride, 10 grams.

Disulphine blue, which is calcium salt of the disulphonic acid of mhydroxy dibenzyldiethyldiamino-triphenylcarbinol anhydride, 5 grams.

Mix with little distilled water into a thin paste then add distilledwater up to 35 oz.

I claim: I l

1. The method of producing color cinematograph pictures which consistsin alternately exposing different sections of a sensitized film througha plurality of filters all of which are of substantially the same tone0f color on the red side of the spectrum and one of which has associatedwith it an opening passing white light.

2. The method of producing a color cinematograph film which consists inexposing Mmmm ' Y altarnatsly substantially' @1m-ng@ 'ated and -buegreen, thev blue" green, coloring heingingpsingwhiie light c. In c0101'mammography appnmtus 'a l arrangd'theren in spaced vlatelation Awhre'byLAUEL @IESE-GREENE.

